dsp architecture details

1. Digital signal processing
Algorithms

2. Why go digital?
• Digital signal processing techniques are
now so powerful that sometimes it is
extremely difficult, if not impossible, for
analogue signal processing to achieve
similar performance.
Examples:
FIR filter with linear phase.
Adaptive filters.

3. Why NOT go digital ?????

4. Why do we need DSP processors?
• Why not use a General Purpose
Processor (GPP) such as a Pentium
instead of a DSP processor?
• What is the power consumption of a
Pentium and a DSP processor?
• What is the cost of a Pentium and a
DSP processor?

5. Digital signal processing Algorithms
• The Sum of Products (SOP) is the key
element in most DSP algorithms:
Such as Convolution, interpolation filter,
decimation filter, FIR filter, DFT,FFT,
DCT, Q-notation.

6. Convolution:

7. Interpolation Filter:
Insert (L-1)
zeros
Low pass
Filter
X(n) Xz(m) y(m)

8. Decimation Filter:
Lowpass Digital
Filter
Down
Sampler
y(n)X(n) X(m)

9. Discrete Fourier Transform
Discrete Cosine Transform

10. Finite Impulse Response Filter:

11. Infinite Impulse Response Filter:

12. Q-notation
• It specifies the number of Fractional
bits.
• Commonly used notation for DSP
implementations is Q15.
Example :16-bit fixed N=4000h
in Q15 we have 0.100 0000 0000 0000b
i.e., N=+0.5